실천하다 means putting an idea or plan into action, so we can say things like,
- 새해의 다짐을 실천하다 = keep one's New Year Resolutions.
- 계획을 실천하다 = 계획을 실천에 옮기다 = put one's plan to work.
- 친구는 내게 했던 약속을 실천했다 = My friend fulfilled the promise he made to me.
- 아무리 좋은 계획도 실천하지 않으면 소용없다 = No matter how good the plan, it's no use if you don't put it into action.